conditional_emit(array<boolean> conditions, array<primitive> features) - Emit features of a row according to various conditions

WITH input as (
selectarray(true, false, true) as conditions, array("one", "two", "three") as features
UNION ALL
selectarray(true, true, false), array("four", "five", "six")
)
SELECT
conditional_emit(
conditions, features
)
FROMinput;
one
three
four
five

element_at(array<T> list, int pos) - Returns an element at the given position